Drill-bit.



at a sa GEORGE WATSON MQALLISTER, SAN FRANCISCO, CALIFORNIA.

JD'RILL-BIT.

lhi fijlfiil.

original application filed March 8, 1911,

To all whom it may concern.-

Be it known that l, GEORGE W. MoALLis- TER, a citizen of the United States, residing at San Francisco, in the county of San Francisco and State of California, have invented a new and useful Drill-Bit, of which the following is a specification in such full and clear terms as will enable those skilled in the art to construct and use the same.

This invention relates to a Well drill bit and its object is to produce a drill bit which will be capable of completing the boring of a well without the removal of the bit there from when once the well is started.

This invention is disclosed in application for patent filed by me in the United States Patent ()flice March 8, 1911, Serial Number 613,064- and of which this application is a division.

A further object of this invention is to produce a drill bit which will be capable of breaking up the core produced in the drilling operations so that it can be washed to the surface with the water forced through the drill rods.

"Another object of the invention is to produce a drill bit which will be capable of per mitting the inflow and outflow through the same of the water used for drilling purposes.

In the drawings, in which the same numeral of reference is applied to the same.

portion throughout the several views, Figure 1 is a plan View of the bit looking at the threaded end thereof, Fig. 2 is a horizontal sectional view of the drill bit on the line 2 2 Fig. 4, Fig. 3 is a side elevation of the drill bit, and Fig. 4 is a vertical longitudinal sectional view of the drill bit showing the positioning of the core breaking cutters.

The numeral 1 represents hard longitudinal segments, of which the bit has two,

while the numeral 2 represents similar sec-- tor like soft segments, which latter segments are of such hardness with respect to the hard segments as to wear away at the point 3 of the bit as rapidly as may be necessary to always leave the bit point in a good shape for cutting purposes. lit will be understood by those skilled in the art that these segments may be secured together by. some such process as electrical welding, or by the Well known thermit process, thus making the parts substantially integral.

Embedded in the hard segments 1, or in the soft segments if so desired, are a series Specification of Letters Patent.

. Patented Mar. 23., 1915..

Serial No. 613,064. Divided and. this application filed January 18, 191%. Serial No. 671,991.

of cutters 3, said cutters projecting toward the center of the drill bit in such a manner as to gradually pare ofl the outside of the core produced by the bit, the upper cutters gt the series projecting to the center of the At the sides the bit is openings 5 extending longitudinally there through, said openings terminating in a shallow groove 6 at the threaded end of the bit, said groove being for the purpose of permitting the water fed to the bit through the adjacent rod to reach said openings even though said rod might not be turned so that the openings through the same would come into exact alinement with the openings in the bit. The upper end of the bit is threaded as shown at 7 and the lower end is cut into any convenient or desirable form for the given rock to be cut. It will also be understood that where a deep hole is to be drilled that the bit is made of such length as will probably be suliicient to complete which is central and a plurality of corebreaking cutters of different lengths extending into the central opening, substantially as described. v

j 2. In a drill bit for rotary-drills, a rod having a plurality of openings therethrough, one of which is central, threads at one end of said rod for connecting said rod to a drill rod, cutting means formed at the other end of said rod and a pluralityof rigid inwardly extending cutters of different lengths secured to said drill rod for the purpose of breaking the core formed thereby, substantially as described.

3. In a drill bit for rotary drills, a. rod having means to secure the same to an adjaprovided with two cent drill rod at one end and having cutting I 'ing and a plurality of successively longer cutters extending from the drill rod toward the center thereof in the central opening therethrough, substantially as described.

5. In a drill bit for rotary drills, a drill rod formed With hard and soft longitudinal segments and having threads at one end and cutting means at the other end, said rod also having a central opening and two other openings extending longitudinally therethrough, a groove in the threaded end of said rod and connecting the two non-central openings therein, and a plurality of cutters projecting into the central opening in said drill rod, the cutter adjacent the drill rod cutting means being the shortest and the other cuttersbeing successively longer until they reach the center of said drill rod, substantially as described.

In testimony whereof I have hereunto set my hand this 11th day of January A. D. 1912, in the presence of the two subscribed Witnesses.

GEORGE WATSON MCALLISTER.

Witnesses:

C. P. GRIFFIN, L. H. ANDERSON. 

